UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

This Amendment No. 3 amends and supplements the statement on Schedule 13D, filed on May 31, 2011, as amended by Amendment No. 1 thereto, filed on October 3, 2012, and Amendment No. 2 thereto filed on December 11, 2012 (collectively, the “Schedule 13D”), by New Mountain Finance Corporation, a Delaware corporation (the “Reporting Person”)(1) with respect to the common membership units (“Units”), of New Mountain Finance Holdings, L.L.C., a Delaware limited liability company (the “Issuer”).  Capitalized terms used herein but not defined shall have the meanings ascribed thereto in the Schedule 13D.  Except as herein amended or supplemented, all other information in the Schedule 13D is as set forth therein.

Item 3.

Source and Amount of Funds or Other Consideration

Item 3 of the Schedule 13D is hereby amended to add the following:

On March 25, 2013, the Reporting Person completed an underwritten public offering of 2,000,000 shares of its Common Stock at a public offering price of $14.30 per share (the “March 2013 Primary Offering”). As a result, pursuant to the LLC Agreement as described in Item 6, the Reporting person used the aggregate net proceeds (after deducting underwriting discounts and commissions) from the March 2013 Primary Offering of $28,400,000 to acquire 2,000,000 Units.

On March 25, 2013, concurrent with the March 2013 Primary Offering, the Reporting Person completed an underwritten public offering of 4,900,000 shares of its Common Stock at a public offering price of $14.30 per share (the “March 2013 Resale Offering”) on behalf of New Mountain Finance AIV Holdings Corporation (“AIV Holdings”). In connection with the March 2013 Resale Offering, AIV Holdings tendered 4,900,000 Units held by AIV Holdings to the Reporting Person in exchange for $67,963,000 of net proceeds (after deducting underwriting discounts and commissions) and the Reporting Person issued 4,900,000 shares of its Common Stock directly to the underwriters for the March 2013 Resale Offering.

Item 5.

Interest in Securities of the Issuer

Items 5(a) and 5(b) of the Schedule 13D are hereby amended and restated in their entirety as follows:

(a) — (b).  The aggregate percentage of Units reported owned by the Reporting Person is based upon 42,578,352 Units outstanding, which is the total number of Units outstanding as of March 25, 2013.

For the aggregate number of securities of the Issuer beneficially owned, the percentage of the class of securities of the Issuer beneficially owned, the number of securities for which the Reporting Person has the sole power to vote or to direct the vote, the number of securities for which the Reporting Person has the shared power to vote or to direct the vote, the number of securities for which the Reporting Person has the sole power to dispose or to direct the disposition, and the number of securities for which the Reporting Person has the shared power to

(1)              Neither the present filing nor anything contained herein shall be construed as an admission that (i) the Reporting Person constitutes a “person” for any purposes other than Section 13(d) of the Act, (ii) the Reporting Person is, for purposes of Section 13(d) or Section 16 of the Act or otherwise, a member of a group or (iii) the Reporting Person is, for the purposes of Sections 13(d) of the Act, the beneficial owner of any securities other than securities directly owned by such Reporting Person.

dispose or to direct the disposition, see the responses to Items 7 through Item 11 and Item 13 on the attached cover page.

Item 5(c) of the Schedule 13D is hereby amended to add the following:

On March 25, 2013, the Reporting Person completed the March 2013 Primary Offering of 2,000,000 shares of its Common Stock at a public offering price of $14.30 per share. As a result, pursuant to the LLC Agreement as described in Item 6, the Issuer issued 2,000,000 Units to the Reporting Person in exchange for the net proceeds (after deducting underwriting discounts and commissions) of the March 2013 Primary Offering.

On March 25, 2013, concurrent with the March 2013 Primary Offering, the Reporting Person completed the March 2013 Resale Offering of 4,900,000 shares of its Common Stock at a public offering price of $14.30 per share on behalf of AIV Holdings. In connection with the March 2013 Resale Offering, AIV Holdings exchanged 4,900,000 Units held by AIV Holdings for 4,900,000 shares of the Reporting Person’s Common Stock and instructed the Reporting Person to issue such shares directly to the underwriters for the March 2013 Resale Offering.

Item 6.

Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer

Item 6 of the Schedule 13D is hereby amended to add the following:

In connection with the March 2013 Primary Offering and the March 2013 Resale Offering, the Reporting Person, the Issuer and AIV Holdings, among others, entered into an underwriting agreement, dated March 20, 2013, with certain underwriters (the “March 2013 Underwriting Agreement”). A more detailed summary of the March 2013 Underwriting Agreement is set forth in the Issuer’s Prospectus dated March 20, 2013, as filed with the SEC on March 21, 2013. This summary is qualified in its entirety by the terms of the March 2013 Underwriting Agreement, which is set forth as Exhibit 99.6, and is incorporated herein by reference.

Item 7.

Material to be Filed as Exhibits

Item 7 of the Schedule 13D is hereby amended to add the following:

99.6                        Underwriting Agreement, dated March 20, 2013, filed as Exhibit (h)(2) to the Post Effective Amendment No. 1 to the Issuer’s Registration Statement on Form N-2 dated March 20, 2013, and incorporated herein by reference.

Date: March 28, 2013

NEW MOUNTAIN FINANCE CORPORATION

By:

/s/ Adam B. Weinstein

Name:

Adam B. Weinstein

Title:

Chief Administrative Officer and Executive Vice President